Does Mounjaro cause heart palpitations?

Feeling your heart race, pound, flutter, or skip a beat can understandably be unsettling, especially when you’re focused on looking after your health. And Mounjaro can cause an increased heart rate. A fast pulse is listed among the common side effects of Mounjaro in the patient leaflet, which means it may affect up to 1 in 10 people. Often, these palpitations are harmless and you can manage them with simple lifestyle adjustments. However, if you develop new or persistent palpitations while taking Mounjaro, seek medical advice rather than assuming they are a routine side effect.

In this guide, we’ll look at what the evidence tells us, other possible explanations, what you can do, and when symptoms need medical attention.

Can Mounjaro cause heart palpitations?

Mounjaro can make your heart beat faster, but an increased heart rate isn’t quite the same as palpitations. A fast pulse is a recognised side effect of Mounjaro, while palpitations are not listed separately in the patient leaflet.

According to Irish Heart, palpitations are the feeling of your own heart beating, or noticing a change from its usual steady rhythm. People describe them as:

• a fluttering feeling in the chest
• the heart racing or pounding
• skipped or extra beats

In other words, a faster heart rate is something that can be measured, while palpitations are something you feel. And palpitations can have many causes that have nothing to do with your medication. So, palpitations on Mounjaro do not necessarily mean Mounjaro is the cause.

Irish Heart also explains that most people experience palpitations at some point in their lives, and they’re usually harmless. Even so, it’s a good idea to speak to a healthcare professional about any new, persistent, or worrying symptoms.

How can Mounjaro affect your heart rate?

Mounjaro can cause a small increase in heart rate for some people. In the patient leaflet, a fast pulse is listed as a common side effect, affecting up to 1 in 10 people.

The official product information from the European Medicines Agency (EMA) gives more detail from clinical trials:

• in studies of people with type 2 diabetes, the biggest average rise in heart rate was 3-5 beats per minute
• in a weight management study of people without type 2 diabetes, 2.4%, 4.9%, and 6.3% of people taking the 5 milligram (mg), 10mg, and 15mg doses had a rise in heart rate of more than 20 beats per minute at two or more visits in a row, compared with 1.2% of people taking a placebo (a dummy treatment)

So, most people in these studies experienced only a small increase in heart rate. Larger increases were uncommon but happened more often at higher doses.

What else can cause palpitations on Mounjaro?

Experiencing palpitations while taking Mounjaro doesn’t automatically mean Mounjaro caused them. There are lots of other common triggers, and some are linked to the changes that can come with treatment, rather than the treatment itself.

Dehydration

Dehydration on Mounjaro is common in people who suffer with certain common side effects like vomiting, nausea, or diarrhoea, which can all cause loss of fluids. The HSE lists feeling like your heart is beating fast as a sign of serious dehydration, so be mindful of that.

Low blood sugar

If you take Mounjaro alongside a sulphonylurea or insulin for type 2 diabetes, low blood sugar (hypoglycaemia) is very common. The leaflet lists a fast heartbeat among the warning signs, along with sweating, dizziness, feeling hungry, and confusion.

Caffeine, alcohol, and nicotine

Irish Heart names smoking, too much tea or coffee, and too much alcohol as common triggers for palpitations. Due to its effects on appetite, Mounjaro can make you tired as you eat less throughout the day. So, if you’ve started relying on extra coffee or energy drinks to get through the day, this could be playing a part.

Stress, anxiety, and excitement

Strong emotions like anxiety, excitement, and stress can all bring on palpitations. Starting a new treatment or making big lifestyle changes can be stressful in itself.

Exercise

Strenuous physical activity is another common trigger. If you’ve recently started exercising more as part of your weight loss journey, you may notice your heartbeat more than before.

Hormonal changes

Hormonal changes during periods, pregnancy, or menopause can cause palpitations, according to Irish Heart.

Other medical conditions and medicines

Some health conditions, such as an overactive thyroid or anaemia, can also cause palpitations. So can some medicines, including certain asthma inhalers and cold and cough remedies. Your GP can check for those if needed.

What can you do about palpitations on Mounjaro?

In many cases, a few simple changes can help you feel calmer and more in control. Irish Heart explains that most often, no treatment is needed other than avoiding potential triggers.

Stay hydrated

The Mounjaro patient leaflet advises drinking plenty of fluids to avoid dehydration, especially if you’re dealing with sickness or diarrhoea. Keeping a water bottle with you through the day is an easy habit to build. Our guide to the benefits of drinking water has more ideas for you.

Cut back on caffeine

Irish Heart recommends cutting down on caffeinated drinks like tea, coffee, and energy drinks, and avoiding stimulants in general. Try swapping these drinks for decaf options or water.

Be mindful of alcohol

Alcohol is also a common trigger for palpitations, and drinking too much can also lead to dehydration. If you notice palpitations after drinking, it may be worth cutting back. For more information, check out our guide to whether you can drink alcohol on Mounjaro.

Find ways to manage stress

Irish Heart suggests relaxation techniques such as meditation, yoga, or mindfulness. Just a few minutes a day can be a good place to start. This is important as stress can also lead to emotional eating, which impact your progress on the medication.

Check your blood sugar (if you have diabetes)

If you take insulin or a sulphonylurea and feel your heart racing, it’s worth checking your blood sugar. Your doctor should tell you how to treat low blood sugar if it happens.

Do palpitations on Mounjaro go away?

For many people, yes. Whether palpitations settle depends on their cause. If they persist, recur or worsen, contact your healthcare professional for assessment.

Irish Heart explains that palpitations can last anywhere from a few seconds to a few days. It’s also worth knowing that Mounjaro’s digestive side effects, like nausea and diarrhoea, are most common when you first start treatment and ease over time for most people. As these settle, the risk of dehydration-related palpitations may ease too.

If your palpitations don’t settle, or they’re affecting your everyday life, speak to our clinicians. They can review your treatment and may suggest a lower dose or a check-up with your GP.

“Palpitations can feel worrying, but if they’re linked to Mounjaro, they’ll often settle as your body adjusts to your dose. If they keep happening or are affecting your day-to-day life, please speak to your clinical team. We can review how you’re getting on and may recommend adjusting your dose or speaking to your GP for further checks.”

Niya MansuriPrescribing Pharmacist

When should you seek medical advice about palpitations?

Most palpitations are not a sign of anything serious, but some symptoms do need checking. Irish Heart advises getting checked by a doctor if your palpitations become more frequent, or if they get worse and come with other symptoms, such as dizziness, fainting, or chest tightness.

Get medical help immediately if a fast heartbeat comes with breathing problems or swelling of your lips, tongue, or throat. The Mounjaro patient leaflet lists these as possible signs of a severe allergic reaction, which is rare.

The HSE also advises calling 112 or 999, or going to your nearest emergency department, if a rapid heartbeat comes with signs of serious dehydration, such as confusion, severe dizziness, or not peeing all day.

If you’d like to talk things through, the Irish Heart Nurse Support Line is available on (01) 668 5001.

Get support throughout your treatment

Noticing your heart racing can be worrying, but you don’t have to work out what’s going on by yourself.

If you’re a myBMI patient, your treatment plan includes ongoing clinical support with side effects. If you have questions about palpitations or any other side effect, our IMC-registered doctors and clinical team are here to help you find a way forward that works for you.

Sources

• Dehydration in adults. (2024) HSE. [Accessed 4 October 2026]
• Heart of the Matter - Heart Palpitations. (2018) Irish Heart. [Accessed 5 October 2026]
• Mounjaro: EPAR - Product Information. (2026) European Medicines Agency. [Accessed 5 October 2026]
• Mounjaro package leaflet: Information for the patient. (2026) Medicines.ie. [Accessed 4 October 2026]
• Palpitations. (2023) Irish Heart. [Accessed 5 October 2026]